He cut an uninspiring figure at the Stadium of Light under former United boss Moyes, with the Black Cats finishing bottom of the Premier League, leading to their relegation. The 22-year-old managed to score only once in 28 games, which was in the EFL Cup against Shrewsbury. His time at Borussia Dortmund in the 2015/16 season was also a mess, where he did not start a single league game.

However, he is desperate to bounce back in the La Liga, while adding that he has great respect for Jose Mourinho, despite not having a great relationship with the manager. The Portuguese manager sanctioned his exit from Old Trafford , who was once considered to be among United's brightest talents under Moyes.

"Obviously, he is a great trainer but I did not have much of a relationship with him," he told Manchester Evening News. "I respect him a lot because he is the one who left the door open for me to leave Manchester United."

"What I want now is to prove that I am a good player and that they were wrong to let me go. I want to grow with La Real and be a better player," he added. "That's my goal for the future."

The Belgium international, who made 66 appearances for the Old Trafford club has signed a five-year deal with Sociedad. The La Liga outfit secured his services for a fee around £9.8m ($12.6m), according to the BBC.